Subtraction

Background 

We've worked with the number line and math symbols to do addition, like 3 + 2 = 5. So what about taking away, also known as subtraction?

Question 

What's 5 - 2? What are some words associated with subtraction?

Answer 

5 - 2 = 3. Subtraction, take away, deduct, subtract, eliminate, minus, less, difference

Analysis  

I'll do the 5 - 2 first.

Let's start by taking a look at the number line. I'll go ahead and place a blue mark for 5:



When we subtract, we want to move to the left on the number line. In this case we're moving two to the left, so let's put a red dot on the spot 2 to the left of 5 (and show that movement with a red line):



This is the graph of 5 - 2 = 3

Now let's talk subtraction terminology.

Words that tells us that we need to subtract include: subtraction, take away, deduct, subtract, eliminate, less, and minus. The numbers that we're using when we subtract are called terms. The answer we get from subtraction is called the difference.

For more information check out these links (comment to add your favourite link): 

Where might you have come from? 

Fact-orials Index

Numbers:

• Counting/Natural Numbers

Operations:

• Addition

Graphing:

• Number Line

Where might we go?

Numbers:

• Negative Numbers

Operations:

• Grouping Terms, Parentheses
• Order of Operations

Operations with different kinds of numbers:

• Addition, Subtraction, and Whole Numbers
• Addition, Subtraction, and Variables

Properties of operations:

• Commutative Property
• Associative Property

Relations:

• Equality
• Inverse Relations